Sunlight Activated, Film Forming Polymer Based on Diazirine Grafted Polycaprolactone

Area of Science:

• Polymer Chemistry
• Materials Science
• Photochemistry

Background:

• Diazirine-grafted polycaprolactone (CaproGlu) is a photoactivatable material.
• It has potential applications as a film-forming sunscreen or a component thereof.
• Understanding structure-property relationships is crucial for optimizing its performance.

Purpose of the Study:

• To investigate the effects of molecular weight, activation temperature, and photocatalyst inclusion on CaproGlu's film-forming capabilities.
• To evaluate the rheological properties and photoactivation kinetics.
• To assess the preliminary skin sensitization potential for topical use.

Main Methods:

• Synthesis of diazirine-grafted polycaprolactone with varying molecular weights.
• Rheological measurements to assess film properties (storage modulus, elasticity, viscosity).
• Photoactivation studies using sunlight and an iridium photocatalyst; skin sensitization assays.

Main Results:

• Polycaprolactone with a molecular weight of 1000 Da provided suitable elasticity and fluidity for spreading.
• Higher activation temperatures reduced viscosity but increased light energy requirements for gelation.
• Inclusion of an iridium photocatalyst accelerated photoactivation kinetics without compromising rheological properties.
• Preliminary assays indicated no skin sensitization for CaproGlu and IrPC formulations.

Conclusions:

• CaproGlu's film-forming properties can be tuned by adjusting molecular weight and activation temperature.
• Photocatalyst inclusion enhances photoactivation efficiency.
• The material demonstrates safety for topical application, supporting its potential as a sunscreen component.